How radiator works? May radiator influence with coolness surrounding? however it switched off?

if you have the thermostatic valve set to ice zero, i presume that's the frost setting and the radiator should become lukewarm,if you take the handle off a thermostatic valve (the bit that you turn), you will see a pin on the top,spray some WD40 on it and keep pushing the pin down and very gently lifting the pin with pliers, careful no to pull the pin out and this should ensure that the valve will operate perfectly